* Neil Horman <nhor...@tuxdriver.com> wrote:
> > etc. For such short runtimes make sure the last column displays
> > close to 100%, so that the PMU results become trustable.
> >
> > A nehalem+ PMU will allow 2-4 events to be measured in parallel,
> > plus generics like 'cycles', 'instructions' can be added 'for free'
> > because they get counted in a separate (fixed purpose) PMU register.
> >
> > The last colum tells you what percentage of the runtime that
> > particular event was actually active. 100% (or empty last column)
> > means it was active all the time.
> >
> > Thanks,
> >
> > Ingo
> >
>
> Hmm,
>
> I ran this test:
>
> for i in `seq 0 1 3`
> do
> echo $i > /sys/module/csum_test/parameters/module_test_mode
> taskset -c 0 perf stat --repeat 20 -C 0 -e L1-dcache-load-misses -e
> L1-dcache-prefetches -e cycles -e instructions -ddd ./test.sh
> done
You need to remove '-ddd' which is a shortcut for a ton of useful
events, but here you want to use fewer events, to increase the
precision of the measurement.
Thanks,
Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
